1. Field of the Invention
The present invention relates to a method of cleaning a chamber of a chemical vapor deposition (CVD) machine and elements within, more specifically, to obtain a cost-effective solution for CVD machine maintenance.
2. Description of the Prior Art
Chemical vapor deposition (CVD) involves changing reactants to solid products through chemical reactions in a chamber, and is one of the most important tools commonly applied in the semiconductor industry. Films for conductors, semiconductors or dielectrics can all be produced by the CVD process. Since the CVD process involves producing films through chemical reactions among gas reactants, the crystallinity and the stoichiometry of the films are better than that of the films produced by sputtering.
Fluoro nitride (NF3) is the default clean gas for the CVD machines made by AMAT, commonly used by semiconductor manufacturers. However, worldwide shortage of flouro nitride in recent years has forced manufacturers to turn to alternative gases such as carbon tetrafluoride (CF4) and perfluoro ethane (C2F6). The end result of the CVD process is the production of a black residual layer that is coated on the surface of the heater and other process kits in the CVD chamber. As the manufacturing frequency and quantity increase, the residual layer becomes thicker so that stress error of the CVD machine occurs more frequently. As well, both the thickness and uniformity of the film produced by the CVD machine are affected.
The common solution to this problem is to adjust the parameters of the CVD machine and that of the process as compensation. However, a great deal of man-hour is needed for the adjustment to lead to the increase in the shutdown period of the CVD machine. Also, as the thickness of the residual layer increases to a certain amount, compensation through parameter adjustment is no longer feasible and replacement of the heaters are required. The current price for a new heater is approximately 40,000 U.S. dollars. Six heaters must be replaced each time, six times per year. In other words, an annual cost of more than 1.5 million U.S. dollars is spent on each CVD machine to solve the problem of the black residual layer. Thus, not only is significant cost required to maintain the CVD machine but also significant man-hours is needed for the daily adjustment of the CVD machine and process parameters to hinder operational management.
It is therefore a primary object of the present invention to provide a method of cleaning a chamber of a chemical vapor deposition (CVD) machine and elements within as a cost-effective solution for CVD machine maintenance.
In the present invention, a method of cleaning a chamber of a CVD machine and elements within is provided to save both cost and effort in the maintenance of CVD machines. In the preferred embodiment of the present invention, a CVD chamber comprises a heater and other process kits. Firstly, a gas mixture of tetrafluoride (CF4) and perfluoro ethane (C2F6) is injected into the chamber. After a surface treatment, comprising a sandblasting step or a polishing step, is performed on the elements, the elements are then immersed in a cleaning solution comprising at least ammonia water (NH4OH) and hydrogen peroxide (H2O2) of a temperature between 40xc2x0 C. to 70xc2x0 C. Finally, the temperature of the cleaning solution is raised so that the residual layer on the surface of the elements can drop from the surfaces of the heater and the process kits or dissolve into the cleaning solution.
It is an advantage of the present invention over the prior art that the cleaning method of the present invention can efficiently reduce the maintenance cost for CVD machines. As well, the residual layer coated on the surfaces of the heater and the process kits can be completely removed without requiring a great deal of man-hours and effort spent on parameter adjustment of the CVD machine and that of the process. Therefore, the shutdown period of the CVD machine can also be significantly reduced.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the multiple FIGS. and drawings.